%0 Journal Article %T Use of Two Sulfonphthalein Dyes for the Sensitive and Selective Extraction-Free Spectrophotometric Assay of Albendazole in Bulk Drug and in Tablets %A Nagaraju Swamy %A Kanakapura Basavaiah %J ISRN Analytical Chemistry %D 2013 %R 10.1155/2013/734027 %X Albendazole (ALB) is a potent benzimidazole anthelmintic used in the treatment of human intestinal helmintiasis as well as of hytatid cysts and neurocysticercosis. Two rapid, simple, sensitive, and selective spectrophotometric methods are presented for the determination of ALB in pharmaceuticals. The methods are based on the formation of dichloromethane soluble 1ˋ:ˋ1 ion-pair complexes (ALBˋ:ˋdye) formed between ALB and sulfonphthalein dyes, bromophenol blue BPB, (method A) and bromothymol blue BTB, (method B). The complexes formed were measured directly (without extraction) at 445ˋnm (method A) and 460ˋnm (method B). The experimental conditions were optimized and the systems obey Beer*s law for 1.5每21.0 and 2.0每32.0ˋ米gˋmLˋ1 ALB for method A and method B respectively. The molar absorptivity and Sandell's sensitivity were calculated to be ˋLˋmolˋ1ˋcmˋ1 and 0.0209ˋngˋcmˋ2, and ˋLˋmolˋ1ˋcmˋ1 and 0.0350ˋngˋcmˋ2 using BPB and BTB, respectively. The limits of detection and quantification were calculated to be 0.01 and 0.03, and 0.16, and 0.49ˋ米g mLˋ1 using BPB and BTB, respectively. The relative standard values for intra-day and inter-day precision were less than 3%, and the accuracy was better than 3% for both methods. 1. Introduction Albendazole (ALB), chemically known as methyl-5-(propyl thio)-2-yl benzimidazole methyl carbamate [1], is widely used as an anthelmintic having a wide spectrum of activity [2]. The drug is official in British Pharmacopoeia [3], which describes a potentiometric titration with perchloric acid in formic acid-acetic acid medium. Quantitative determination of ALB in dosage forms has received wide attention and several methods have been reported and include titrimetry in nonaqueous medium [4, 5], redox titrimetry [6每12], UV spectrophotometry [13每17], spectrofluorimetry [18, 19], voltammetry [20每22], high performance liquid chromatography [23每27], and high performance thin layer chromatography [28, 29]. Several visible spectrophotometric methods, both direct and indirect, are found in the literature for the determination of ALB in pharmaceuticals. Basavaiah et al. [30] in their methods treated ALB with a known excess of NBS in HCl medium, and the unreacted oxidant was reduced by iron(II) and the resulting iron(III) was complexed with thiocyanate or tiron offering two sensitive methods. Two more indirect methods [31] involving NBS-metol-sulfanilamide and NBS-celesteine blue as chromogenic systems have been proposed by Sastry et al. Several other reaction schemes involving chloramine-T-methyl orange or indigocarmine [6], %U http://www.hindawi.com/journals/isrn.analytical.chemistry/2013/734027/